This invention relates generally to image data multiplexing, recording and display control apparatus and methods and an image data recording medium, and more particularly is directed to such apparatus, methods and a recording medium arranged so as to be able to display at correct aspect ratio image data produced, recorded and transmitted with different aspect ratios.
Television is broadcast in Japan, the United States and elsewhere using the so-called NTSC standard, for which an aspect ratio of 4:3 is established. For this reason, conventional display equipment, such as television receivers and monitors, mostly have their aspect ratios fixed at 4:3. However, with the recent increase in high quality or definition television broadcasts, typified by HiVision, which employ an aspect ratio of 16:9, television receivers with the wider aspect ratio of 16:9, the so-called wide screen televisions, are becoming increasingly popular.
As a result, the image sources that are produced and broadcast are also tending to have the wider 16:9 or other aspect ratios.
Image data for display on a screen having this 16:9 or other wider aspect ratio may undergo a change or correction of the aspect ratio prior to transmission, so that it can be shown on displays with a 4:3 aspect ratio.
For example, FIG. 1A shows a screen with a 4:3 aspect ratio. Image data intended for display on this screen is transmitted without alteration and, of course, can be displayed as received. However, in comparison, image data for a screen with a 14:9 aspect ratio is transmitted in the so-called letterbox mode, as shown in FIG. 1B, that is, is transmitted after dark or non-image portions are added above and below the active image region to provide an overall aspect ratio of 4:3. Alternatively, image data for a screen with a 14:9 aspect ratio may be compressed in the horizontal direction of the screen in the so-called squeeze mode, as shown in FIG. 1E, whereby it is converted to image data for a 4:3 aspect ratio screen before being transmitted.
Moreover, image data for a screen with a 16:9 aspect ratio may be transmitted in the letterbox mode, as shown in FIG. 1C, that is, after dark or non-image portions are added above and below the active image region having the aspect ratio of 16:9 to provide an overall aspect ratio of 4:3 for broadcast. The dark portions in this case are wider than in the case of the image data for a screen of 14:9 aspect ratio as in FIG. 1B.
Alternatively, image data for a screen with a 16:9 aspect ratio can be transmitted in the squeeze mode whereby the image is compressed in the horizontal direction so as to become a 4:3 aspect ratio screen, as shown in FIG. 1F.
Image data for a CinemaScope screen with approximately a 2:1 aspect ratio may be transmitted in the letterbox mode, as shown in FIG. 1D, with even wider dark or non-image portions added above and below the active image region than is the case for the screen shown in FIG. 1C with a 16:9 aspect ratio, before being transmitted so that the received signal can be displayed on a screen with an aspect ratio of 4:3.
Furthermore, image data for a CinemaScope screen with an approximately 2:1 aspect ratio, even if compressed in a squeeze mode in the horizontal direction with a compression ratio converting it from 2:1 to 4:3, has additional dark portions added above and below the active image region after the compression in the horizontal direction since it cannot otherwise be fitted to the 4:3 aspect ratio of the screen on which it is to be displayed, as shown in FIG. 1G. The images shown in FIGS. 1A-1G, respectively, can be received and displayed without further adjustment on displays having a 4:3 aspect ratio. on the other hand, a display or television receiver or monitor 80 with a screen having a 16:9 aspect ratio may be comprised as shown in FIG. 2. Video signals input via an antenna, cable or the like, after demodulation in a TV signal demodulator circuit 81, are output for display to a CRT 85 having a 16:9 aspect ratio through a controllable horizontal filter 82 and a controllable vertical filter 83. In accordance with instructions from the viewer provided by means of a remote controller or the like (not shown), a controller 84 is made to suitably operate horizontal filter 82 or vertical filter 83.
More specifically, as shown in FIG. 3A, for example, when received images with a standard 4:3 aspect ratio (normal images) are demodulated and output from television signal demodulator circuit 81, the viewer uses the remote control to switch on horizontal filter 82 and to switch off vertical filter 83. By this means, on CRT 85 having a 16:9 aspect ratio, as shown in FIG. 3D, dark or non-image portions are added to the display at the left and right-hand sides of the active, image region having a 4:3 aspect ratio.
When data transmitted in the letterbox mode with the overall aspect ratio of 4:3, as shown in FIG. 3B, is provided as the video input in FIG. 2, the viewer uses the remote control to switch off horizontal filter 82 and switch on vertical filter 83. At this time, vertical filter 83 performs a process whereby it removes the dark portions added above and below the active image region and selects only the active image region having, for example, the original aspect ratio of 16:9. By this means, image data having a 16:9 aspect ratio can be normally displayed on CRT 85 as shown in FIG. 3E.
On the other hand, as shown in FIG. 3C, where images processed in the squeeze mode are transmitted with the 4:3 aspect ratio, the viewer uses the remote control to switch off both horizontal filter 82 and vertical filter 83. As a result, an active image region with a 16:9 aspect ratio is normally displayed on CRT 85, as shown in FIG. 3F.
The manual switching of horizontal filter 82 and vertical filter 83 in this way is relatively inefficient. Therefore, there are some television sets where, for example, correction data corresponding to the corrections, if any, to be made in the aspect ratio are transmitted during the vertical blanking interval of the television signal being transmitted, and such correction data are separated out in television signal demodulation circuit 81 and output to controller 84 for automatically controlling filters 82 and 83, as required.
In such case, controller 84 controls horizontal filter 82 and vertical filter 83 not only in response to user instructions from the remote controller but also in response to signals from television signal demodulator circuit 81. In this way, the viewer no longer needs to always effect manual control, and the efficiency of the operation is improved.
However, the insertion of this kind of correction data into a specific line during the vertical blanking interval cannot be employed where the image transmitted or recorded has been digitized. In other words, where a video signal is digitized for transmission, since data in the vertical blanking interval are in effect mostly useless, the specification for such digitizing stipulates that data in the vertical blanking interval are not transmitted or recorded. As a result, even if correction data is inserted within the vertical blanking interval, this correction data is eliminated prior to transmission or recording if the data is digitized.
Furthermore, there are three potential variations for insertion of the dark or non-image portions in the letterbox mode, particularly in respect to the positions thereof relative to the active image region. For example as shown in FIG. 4A, the active image region may be positioned in the middle, that is, vertically centered between two dark portions; at the top, that is, above a single dark-portion, as on FIG. 4B; or at the bottom, that is, below a single dark-portion, as in FIG. 4C.
Moreover, screens may be provided with subtitles, logos, symbols and the like, at various locations in respect to the active image region in the letterbox mode shown in FIG. 5A. For example, subtitling (ABC) may be overlayed and positioned in the active image region as shown in FIG. 5B, or the subtitling may be positioned in one or the other of the dark portions, as shown in FIG. 5C. Moreover, as shown in FIG. 5D, there may be multiple superimposed displays in the dark portions in the form of not only subtitles, but also logos, symbols, marks and other types of patterns.
Since the data for indicating the various display positions of the active image region, as in FIGS. 4A-4C, and for indicating the display positions of subtitles, logos, symbols and the like, are arranged to be transmitted in analog broadcasts by insertion in a specified line in the vertical blanking interval, this data also cannot be used when the image data is transmitted or recorded in digital format in which case, in the course of compression, the data in the vertical blanking intervals are eliminated.
Accordingly, it is generally an object of the present invention to avoid the previously mentioned disadvantages of the prior art.
More particularly, it is an object of the present invention to permit a video signal transmitted or recorded and reproduced in one aspect ratio to be automatically corrected for display by a television receiver or monitor having a screen with a different aspect ratio even when the video signal is transmitted and/or recorded in digital format.
In accordance with an aspect of the invention, an image data multiplexing device comprises means which supplies digital image data which has been compressed and corrected for aspect ratio, for example, as in the letterbox or squeeze mode, means for generating correction data for further correcting the aspect ratio of the digital image data, and means for multiplexing the digital image data and the correction data from said means for generating.
According to another aspect of the invention, an image data multiplexing method comprises the steps of supplying digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, generating correction data for further correcting the aspect ratio of the digital image data, and multiplexing the digital image data and the correction data.
According to another aspect of the invention, an image data recording device comprises means which supplies digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, means for generating correction data for further correcting the aspect ratio of the digital image data, means for multiplexing the digital image data and the correction data from the means for generating, and means for recording on a recording medium the data multiplexed by the means for multiplexing.
In accordance with still another aspect of the invention, an image data recording method comprises the steps of supplying digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, generating correction data for further correcting the aspect ratio of the digital image data, multiplexing the digital image data and the correction data, and recording the multiplexed data on a recording medium.
In accordance with still another aspect of the invention, an image display control device comprises means for separating digital image data and correction data from multiplexed data containing digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, and correction data for further correcting the aspect ratio of the digital image data, and means for controlling further correction of the aspect ratio of the separated image corresponding to the separated digital image data according to the separated correction data.
In accordance with a further aspect of the invention, an image display control method comprises the steps of separating digital image data and correction data from multiplexed data containing digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, and correction data for further correcting the aspect ratio of the digital image data, and controlling the correction of the aspect ratio of the image corresponding to the digital image data according to the separated correction data.
In accordance with a still further aspect of the invention, an image display control device comprises means for separating digital image data and correction data from multiplexed data containing digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, and correction data for further correcting the aspect ratio of the digital image data, and means for generating a correction signal indicating the correction state of the aspect ratio of the image corresponding to the digital image data according to the separated correction data and for superimposing said correction signal on the signal corresponding to the separated digital image data.
In accordance with yet another aspect of the invention, an image display control method comprises the steps of separating digital image data and correction data from multiplexed data containing digital image data which has been compressed and corrected for aspect ratio, as in the letterbox or squeeze mode, and correction data for correction of the aspect ratio of the digital image data, generating a correction signal indicating the correction state of the aspect ratio of the image corresponding to the digital image data according to the separated correction data, and outputting said correction signal by superimposing it on the signal corresponding to the separated digital image data.
In accordance with yet a further aspect of the invention, an image data recording medium on which compressed digital image data is recorded, is characterized in that, in addition to compressing, correcting the aspect ratio of and recording the digital image data, correction data for further correcting the aspect ratio of the digital image data are multiplexed and recorded with the digital image data.